Is it a bird? Is it a plane? No, it's super-sterling!

The British pound has soared, bouncing off a 2013 low of $1.486 in early July to reach a year-to-date high Tuesday of $1.626, a 9.4% rise. The move has confounded many who were betting against sterling, believing that a US recovery and a less dovish Federal Reserve should lift the dollar. A further rise can't be ruled out, but the sterling rally may yet rest on shaky foundations.